Copyright © Future Technology Devices International Limited

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FT600Q-FT601Q IC DatasheetDatasheet

Version 1.04

Document No.: FT_001118

Clearance No.: FTDI#424

Figure 6.1 & 6.2 illustrate the FT60x in a typical USB bus powered design configuration. A USB bus

powered device gets its power from the USB bus via an external LDO stepping the voltage down to

+3.3V.

A ferrite bead is connected in series with the USB power supply to reduce EMI noise from the FT60x and

associated circuitry being radiated down the USB cable to the USB host. The value of the Ferrite Bead

depends on the total current drawn by the application.

6.2

Self-Powered Configuration

Figure 6.3 Self-Powered Configuration

Figure 6.3 illustrates the FT60x in a typical USB self-powered configuration. A USB self-powered device

gets its power from its own power supply, VCC33 and VCCIO, and does not draw current from the USB

bus. The basic rules for USB self-powered devices are as follows –

i)

A self-powered device should not force current down the USB bus when the USB host or hub

controller is powered down.

ii) A self-powered device can use as much current as it needs during normal operation and USB

suspend as it has its own power supply.

iii) A self-powered device can be used with any USB host, a bus powered USB hub or a self-powered

USB hub.